I started to notice an algea problem about three weeks ago when I came home from Indiana. I left about July 15. Before I did the water change and everything was running fine. Two weeks later I come home to see that my tank had a bunch of green algea on the front, a lot of what looked like brown/black fuzz all over the plants and rock substrate. On my Betta log there appeared to be a bunch of white slime. I thought that a large water change and a little bit of salt could help. Well it got worse and now the front of my tanks is a nice shade of green and the plastic plants and rocks have purple algea growing on them. And the 'white slime' is purple as well. What should I do now? I would like to cycle the tank but that is pretty hard to do without a kit, so I treat my tank as uncycled, changine out about 12 cups every week.

Other info that may help:
My tank is 5gal.
Filtered
Uncycled
Weekly water changes of approx. 12 cups
Light is on for about 13 hours; from 7A.M until about 11P.M.
All artifical decor. Plants are all plastic.
One Betta fish, only tank occupant.

Basically I would like to know what is going on and how to fix it and prevent it from happening again. Obviously I am going to have to clean the tank out, but that would mean killing what little beneficial bacteria I may have. Being a uncycled tank it probably doesn't matter much. Should I add anything? Plants, maybe a shrimp if my Betta tolerates it?

Well, first I would limit your sunlight to your tank, as well as your artificial light. 10 should be ideal, but no more then 12. 10+ promotes algae growth.

As for your algae, check your nitrate and phosphate levels. Clean your tank thoroughly with a phosphate absorbing resin. If it doesn't clear up (honestly I don't think those two things along will do it), isolate your betta, and goto PetSmart and pick up 4-6 otocinclus catfish. They'll clear it up right away, and hold onto your receipt and return them before the 15-day period. Should be good to go after they clean everything up.

Thanks for the suggestion on the fish but that may not be an option for me. I am going to limit the light hours, and will start turning it on when I get home instead of when I leave. Probably the best way to do it considering something could happen while I'm gone.

I know this is a shot out of water but is there anyway I could get away by haveing a snail in there? Even with heavy water changes? For now I am going to wipe down the sides.

Nerite snails are very excellent for cleaning up algae.
But be aware that snails of any type poop quite a bit. What goes in must come out. So you will defenitely need a siphon to clean up the gravel, and possibly more frequent water changes. Keep an eye on your parameters, especially ammonia since the extra bio load will add on to that.

Only get one snail, your tank can hold one betta and one nerite snail :) Nerite snails stay small, my bigger one is smaller than a nickel.

Once the algae is gone, you will need to put the snail in a seperate cup to feed it. With a nerite, you can give algae wafers and zucchini.. Feeding the snail in the tank will result in your betta stealing the snail's food. So not only would the snail go hungry but your betta will become bloated with food that has no nutritional value to the fish. :)